[CI] Prevent ccache crosstalk by building in separate directories

Summary:
ccache is currently turned off for sanitizer builds due to crosstalk
polluting the builds. Buiding in separate directories fixes the issue.

Test Plan: Build the CI sanitizer build plans.

Reviewers: #bitcoin_abc, majcosta, jasonbcox

Reviewed By: #bitcoin_abc, majcosta, jasonbcox

Subscribers: jasonbcox, majcosta

Differential Revision: https://reviews.bitcoinabc.org/D6551